Squeezing roll

ABSTRACT

This disclosure relates to a device for passing webs through rolls to remove or squeeze liquid from the webs. The rolls are made with a covering of a thin layer of a synthetic material. For example, a roll having a 1 to 5 mm layer of polyurethane is useful for squeezing and dewatering textile webs.

United States Patent Urban 1 Sept. 11, 1973 1 SQUEEZING ROLL 3,196,520 7/1965 [75] Inventor: Peter T. Urban, Meerbusch-Osterath, Germany 3:475:803 11/1969 3,490,119 1 1970 [73] Ass'gnee' Edward Kusms Masch'nenfabr'k 3,638,292 2 1972 Gaghan 29 113 AD Krefeld, Germany [22] Filed: Apr. 22, 1971 Primary ExaminerAlfred R. Guest [21] ApPl- N05 1361316 Att0rney--Kenyon & Kenyon Reilly Carr & Chapin [30] Foreign Application Priority Data A r. 23, 1970 Germany P 20 19 708.4 57 ABSTRACT 52 us. c1 29/116 AD, 29/132 This disclosm relates to a device f passing u H through rolls to remove or squeeze from the l Field of Search 29/1 13 AD, 1 16 webs. The rolls are made with a covering ofa thin layer 29/132 of a synthetic material. For example, a roll having a 1 to 5 mm layer of polyurethane is useful for squeezing References Clted and dewatering textile webs.

UNITED STATES PATENTS 2,908,964 10/1959 Appenzeller 29/116 AD 2 Claims, 2 Drawing Figures PATENTEUSEH 1 ma FIG] INVENTOR 'IEl-r' UR SQUEEZING ROLL THE INVENTION This invention relates to a roll for squeezing liquid from textile webs, paper webs and similar webs wherein the operating roll surface consists of a thin layer of synthetic material.

One of the factors which determines the effectiveness of squeezing of textile or similar webs is the hardness of the roll. Under the rolls pressure the roll surface deforms to a degree in the roll nip depending on its hardness. A pressure zone of a certain width is formed within which the pressure distribution declines towards the margin of the pressure zone. Following this pressure drop the liquid moves within the web out of the area of the actual roll nip. The fiber structure of the web causes a certain resistance to the flow of liquid which results in a limited flow velocity in the web. The longer the path which a particular liquid particle has to travel in the area of the roll nip, or the broader the pressure zone, the worse the squeezing effect. Broader pressure zones result when using rolls with soft surfaces. Although a greater softness of the roll gives a greater penetration through uneven portions of the web, this advantage is offset by the drawback of a broad pressure zone.

An increase of the applied pressure between a pair of rolls only slightly increases the squeezing effect because the increased width of the pressure zone detracts from part of the effect. The relation of the pressure zone width to the applied pressure naturally diminishes with hard rolls. Then high rollpressure can be applied without resulting in an undesirably widening of the pressure zone. Therefore, de-watering rolls may be coated with a hard plastic.

A narrow pressure zone may be obtained, for purely geometric reasons, when the roll diameter is small. The use of deflection-free rolls, particularly the so-called swimming rolls, makes an equal application of high pressure over the entire length of the roll possible at small roll diameters.

The use of increased pressure is limited since webs are made of fibers which are crushed with very high pressure.'.The roll pressure must be carefully selected to avoid damaging the fiber.

The limit of the squeezing effect achieved when using smooth rolls which have compact surfaces is improved by fiber rolls wherein the roll body consists of thin discs layered upon each other and compressed which consist of a latex-saturated nonwoven fabric. This is due to the penetration caused by the specia structure of the roll surface of the roll into the fiber space of the web, particularly into woven or knitted textiles.

In some technical fields such as working with webs of textile material, paper or similar materials, improved squeezing results remain to be achieved. When a web retains a slight dampness, the energy costs for further treatment are high. However, for certain dyeing treatments the maximum liquid withdrawal is important.

An object of this invention is to produce improved squeezing effects without the use of a pressure which would damage the treated web. I

Surprisingly, it has been found that a remarkable improvement occurs, compared to the results so far achieved with the fiber rolls, when the operating roll surface is constructed with a coat of less than 5 mm thickness. Excellent results are obtained when treating lighter webs of fiber materials. The improvement may at least be partially based on the small width of the pressure zone compared to the known rolls with considerably thicker plastic coats. When pressing the rolls coats together a certain absolute approach of the cooperating rolls means a considerable larger relative compression of the plastic coating than at a thick plastic coat and a corresponding quicker increase of the elastic counter force. The necessary roll pressure is also achieved when adjusting the roll just a little and when deforming the roll just a little in its roll nip and corresponding small width of the pressure zone.

Of course, the stress of the thin roll coat in the roll nip is extraordinary large. While rubber coatings were destroyed after a few roll rotations, tests have shown that polyurethane is a working material which brings particularly useful life times. While it depends on the material to be squeezed when using solid plastic rolls whether a harder or a softer roll brings the better results, the thin coats according to this invention showed that the best results can be obtained by the use of a relatively soft coat.

A preferred embodiment is provided with a polyurethane coat of l to 3 mm thickness having a hardness of about to shore A. With this roll squeezing effects could be achieved with certain materials which come close to removing all water but that retained by fiber swelling, i.e., close to the fibers moisture absorption.

Rolls of relatively small diameter are preferred, such as about to 300 mm in diameter. Such rolls deflect unless special provisions are undertaken under the high working pressures used over the width of the web which leads to a lower pressure in the middle of the web. In order to bring out all the advantages of the invention and to obtain the desired low moisture content equally over the entire working width the inner roll is preferably constructed as a deflection-free roll, particthe plastic materialthe roll is finished in the usualway.

An embodiment of the invention is shown in the drawing.

FIG. 1 shows a side view of a roll pair one of which is a roll according to invention, partially in longitudinal cross section;

FIG. 2 shows a cross section according to line 11- in FIG. 1.

The preferred embodiment shows a roll pair 1, 2 of which at least the upper one roll 1 is constructed as a swimming roll. Both rolls may be of the same construction. The swimming roll 1 comprises a rotating roll body 3 which is supported on a stationaryinside beam 4. Sealings Sand 6 are provided which separate the inner space between the inner beam 4 and the roll body 3 into two longitudinal chambers 7 and 8. Longitudinal chamber 8 facing the counter roll 2 can be loaded by pressure means through a feed 9. The force applied by the pressure means is equally transmitted ontothe roll body whereby the inner beam 4 absorbs the force and can deflect somewhat without impairing the equality of the pressure of roll body 3.

On the outside of roll body 3, a thin polyurethane coat of about one to five millimeters is applied which comprises the working roll periphery. The coating in the drawing is not to scale; the coating was drawn thicker so it is clearer. The best results are obtained at a relatively low level of hardness of the coating of about 75 to 85 shore A.

The table at pages 8 11 shows the improvement obtainable with the roll of this invention. The table indicates the residual moisture content after squeezing based upon the air-dry weight of the material. Except where indicated otherwise the tests were made with a working pressure of 50 kg/cm at a working speed of 30 m/min, with rolls of equal diameter of 240 mm.

The perlon fiber roll consisted of latex-saturated perlon fiber non-woven fabric discs which are arranged on the roll body and are pressed together to a compact roll. PU is polyurethane, the figure below the material indication states the hardness of the roll in shore A. The thickness of the coatings on the rolls are indicated in the headings of the columns, and were from 1 to 15 mm. The coatings for the rolls of columns 2 6 were 15 mm. The gram-figures stated for the different materials are the figures for the weight per unit area of the corresponding material.

The table shows that an improved squeezing effect was obtained for the rolls having a thin coat compared to the usual rolls having a thick plastic coat. An increase of the working pressure did not lead to considerable improvement, but resulted in an increased stress on the material. The improvement made with the invention is relatively small when treating especially heavy materials. This is understandable because the thickness of the material is already comparable with the coat thickness of the roll. The coat of the roll, if it is supposed to conform to the material and penetrate the unevenness of the surface, is subject to relative considerable stretch.

On the other hand the improvement is particularly great for materials which are relatively thin and are not very compressible and therefore have large interspaces which remain filled with liquid. Here the residual moisture contents of the other homogeneous plastic rolls are higher than the values achievable with the invention which reach close to the residual moisture caused by fiber swelling.

In most cases the result obtained is clearly superior to the perlon fiber roll. Again, exceptions are the especially heavy materials. The roll according to the invention and the perlon fiber roll show about the same achievements when treating wool. The roll having the 1 mm coating shows a clearly superior effect when treating synthetic knitted material and light cotton material compared to the roll having a 3 mm coat.

Although the table shows the effect upon textile materials, the invention is not limited to this area of application. The roll according to this invention is also suitable, for example, for paper production and similar fields.

What is claimed is:

M partinerit on the' nip side of the roll, and another compartment on the opposite side from the nip,

means to seal said first compartment at each end of said shell,

means in said shaft adapted to deliver a fluid pressure to said first compartment, and

a polyurethane shell having a Shore A hardness of about to 85, and a thickness of about 1 to 5 mm, affixed to and around said hollow shell.

2. A roll according to claim 1 having a diameter of from to 300 mm. 

2. A roll according to claim 1 having a diameter of from 140 tO 300 mm. 